The present Invention relates to a flexible sound dampening and heat and corrosion resistant polymer coating composition.
Many transportation vehicles, electronic device apparatuses, and machines are subjected to noise and vibration due to the environments within which they operate. Such noise and vibration can present problems in the use or function of the particular device or apparatus and in turn, become annoying or harmful to the users of such devices or apparatuses. In many applications, noise and vibration are reduced by the placing of extensional dampers on the devices or apparatuses being used. Extensional dampers are composite pads comprised of a viscoelastic polymer or resin, filler and additive composition layer having on one side of such layer a pressure sensitive or hot melt adhesive. However, such pads are difficult to affix to or shape around odd shaped parts, i.e. automotive parts.
In the transportation industry, automobiles have been required to become more and more energy efficient because of more stringent governmental energy restrictions. To accomplish this purpose, automobiles have been made smaller and of lighter weight. In particular, automobile parts have been fabricated with lighter gauge metal in an effort to reduce the total weight of the automobile. Accordingly, it has become necessary to find a means to protect the automobile from corrosion for as long a period of time as prior heavier metal parts accomplished and too find further ways to increase the energy efficiency of automobiles by reducing the overall weight of the automobile.
An avenue pursued to increase energy efficiency in automobiles has been to improve automobile mufflers by reducing weight while improving performance. As shown in FIG. 1, prior art mufflers are constructed with standard inside muffler components 5, two separate steel wraps, an inside wrap 10 and an outside wrap 20 with an air space 30 in between. Both steel wraps are necessary to attain the requisite sound dampening and life requirements for the muffler system. The problem with prior art mufflers is that they cannot be reduced in size or weight because a muffler needs the double wrap construction to adequately dampen the sound of the engine. Thus, a coating of some sort would be ideal to place on mufflers to eliminate the need for the inside wall of the muffler and thereby reduce the weight of the muffler and increase the overall efficiency of an automobile. The coating would have to be able to reduce noise and provide thermal insulation of the muffler. Unfortunately, present technology in high temperature coatings does not include products that have insulating and acoustic properties sufficient to allow elimination of the inside steel wall.
Various types of coatings have been placed in or sprayed on parts of the underside exterior surfaces of automobiles. Such coatings are usually used for corrosion protection by providing abrasion or stone-impact resistance for the painted surfaces. Typically such coatings are tough, elastic polyvinyl chloride based and do not provide significant noise and vibration reduction. In some embodiments, epoxy or modified epoxy resin formulations are used as electro-deposition coatings for corrosion protection. Unfortunately, the epoxy or modified epoxy resin formulations usually form brittle or highly cross-linked networks, at thicknesses, which have limited effect with respect to reducing weight, reducing noise and providing thermal insulation.
Another prior art coating is a silicone heat-resisting paint consisting principally of silicone resin or modified silicone resin, metallic zinc and inorganic pigment. However, the paint coating provides little if any effect with respect to reducing noise. This coating cannot be used to eliminate the need for a double wrap muffler construction because it does not have any acoustic properties. Thus, it cannot further reduce the weight of the muffler system by eliminating one of the steel wall of the prior art muffler. In the prior art, no high temperature coatings exist that possess both insulating and acoustic properties sufficient enough to eliminate the inside steel wall of a vehicle muffler.
Further, the need for a coating with acoustic, thermal insulating, and corrosion resistant properties is not limited to the automotive industry. One skilled in the art understands that such a coating could have many applications and solve many different problems in a wide array of technologies. Thus, what is needed is a multifunctional coating which provides noise and weight reduction in combination with thermal insulating and corrosion resistant properties. What is further needed is such a coating which is sprayable and can easily be placed or coated on odd shape parts and which eliminates the need for the dual wall construction of mufflers.
A multifunctional coating which provides noise reduction and weight reduction in combination with thermal insulating and corrosion resistant properties. The composition comprises an epoxy resin with a weight per epoxide of 175 to 950, a mixed methyl-phenyl hydroxyl functional silicone polymer, a catalyst, a silane, an anti-corrosive pigment, an inert film reinforcing pigment, calcium silicate fibers, a mixture of ground synthetic silicone rubber, silica, and fillers, and an organic solvent.